Likewise, the calculation of rectum and bladder doses made with ICRU reference points, not with rectum and bladder volumes, may not reflect the actual organ doses. In addition, sigmoid colon and small bowel in the pelvis may be in close proximity
to the Alisertib datasheet BRT sources during application, and the doses to these organs should also be assessed. Since the ICRU did not define standard points for the sigmoid colon and small bowel, it is not possible to evaluate doses to these organs with conventional plans. To overcome such problems, CT-guided 3D BRT treatment planning has been used successfully for customizing the dose distribution according to tumor extent and providing detailed dose-volume information on the target volumes and surrounding tissues [12, 17–21]. Some investigators have reported that the point A-dose in the conventional plan overestimates the target volume dose coverage [10–12]. In addition, more advanced tumor stages and larger target volumes receive less
coverage with the prescribed dose, which may result in poor local control [12, 22]. Datta et al. demonstrated that the percentage of tumor encompassed within the point-A dose envelope ranged from 60.8% to 100%, and this percentage depended on the tumor volume at the time of ICBT . In the current study, we demonstrated that the mean percentage of GTV and CTV encompassed within the point-A 7 Gy isodose level was 93.1% (74.4%–100%) and 88.2% (58.8%–100%), learn more respectively. Inadequate tumor coverage could significantly influence the treatment outcome in patients, especially in those who have partial regression of tumors with gross residual tumor after ERT. Thus, tumors with larger volumes at ICBT were more likely to have portions outside the 7 Gy prescribed isodose line (Figures 2 and 3). Initially, Kim et al. demonstrated that the CT-plan would be beneficial in patients with large CTVs, which could not be fully encompassed by the 100% isodose line . In the current study, Urease the GTV and CTV were larger in group 2 than in group 1; therefore, the CT-plan would be most beneficial in group 2. Although the isodose
matrix volumes did not differ between the two groups with the conventional plan, these volumes were higher in group 2 with the CT-plan (Table 2), which may cause a significant incremental dose to the neighboring tissues, mainly the bladder and sigmoid colon (Table 3). Although tumor shrinkage before BRT applications may take place after ERT, the initial tumor stage, which reflects the tumor extension, may negatively impact tumor coverage [1, 22, 23]. Kim et al. demonstrated that GTV but not CTV increased with advanced stages . They also found that the percentages of the GTV encompassed by the 6 Gy isodose line were 98.5%, 89.5%, 79.5%, and 59.5% for stages IB1, IB2, IIB, and IIIB, respectively. In our study, the GTV and CTV appeared to increase with more advanced clinical stages.